[chbot] ESCs for RC models

[Mark Atherton]

That idea should work fine.

The clever bit is to figure out how to source the large drive currents 
required to overcome the input capacitance of the output FETs, allowing 
the FETs to switch quickly (and not generate heat).

Part 2, is to manage all of the circulating currents so that everything 
goes where it is supposed to.

Part 3 is to specify capacitors which can manage 2 above without 
overheating, or exploding :)

In all seriousness, have a look around before you climb in : 
http://www.robotpower.com/products/osmc_info.html appears to have gone 
through quite a few revisions, and may be stable now.

The HIP4081A is a popular H bridge driver, has hi and low side 
translation, can deliver a couple of amps gate current, and has an 
overlap generator so that top and bottoms FETs do not switch on at the 
same time.

A 'typical' output FET may have 5000pF gate capacitance, and for a 10V 
change in 100ns will need around 500mA peak. Allowing gate voltage to 
change slowly can generate lots of heat (since the FETs will spend time 
in their linear region, which is V undesirable).

Anyway, just my 2c

Regards, Mark

On 24/02/2018 5:39 PM, Andrew Errington wrote:
> Thanks for your suggestions everyone. I might get lucky if I can get 
> an ESC without braking (or can be configured to turn that off), 
> otherwise a micro to read servo control pulses and drive an H-bridge.
>
> Best wishes,
>
> Andrew
>
> On Feb 24, 2018 11:31 AM, "Robin Gilks" <robin at gilks.org 
> <mailto:robin at gilks.org>> wrote:
>
>
>     > Hi Synco,
>     >
>     > Thanks for replying. I'm sorry, I should have mentioned the
>     motor type.
>     > Simple brushed dc motors.
>     >
>     > I could build something, but I'm looking for an off-the-shelf
>     module.
>     > Popular and cheap fits the bill.
>     >
>     > Thanks,
>     >
>     > Andrew
>     >
>
>     I used these to drive the 24v wheelchair motors on my walnut washer.
>
>     https://www.aliexpress.com/item/Double-BTS7960B-DC-43A-Stepper-Motor-Driver-H-Bridge-PWM-For-Arduino-smart-Car/32647125360.html
>     <https://www.aliexpress.com/item/Double-BTS7960B-DC-43A-Stepper-Motor-Driver-H-Bridge-PWM-For-Arduino-smart-Car/32647125360.html>
>
>     They don't even get warm @ 5A
>
>     No idea if there is anything available here for less that 5 times
>     as much!
>
>
>     --
>     Robin Gilks
>
>
>
>
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